This invention relates to an apparatus for assembling vehicle wheels and more particularly to an apparatus for assembling a wheel disc within a wheel rim.
It is common in the manufacture of vehicle wheels to assemble the wheel disc within the wheel rim after the parts have been separately manufactured. The wheel disc is formed in a stamping operation from a generally square blank of metal and includes a center portion containing the bolt holes and axle hole and a circular outer edge portion having a plurality of axially extending circular flange portions formed from the corner portions of the blank. The axial terminal edges of the axially extending flange portions of the wheel disc lie in radial planes which are located at varying axial distances from the plane of the center portion of the wheel disc. The wheel rim is formed in a rolling operation from a welded ring of coil metal stock. It includes the usual outer or terminal flanges, tire bead seat flanges, and a drop center flange.
It is known to assemble vehicle wheels by force fitting the axially extending flange portions of the wheel disc within the drop center flange of the rim. In such an operation, the wheel rim is located in a horizontal position, the center portion of the wheel disc is located within the opening of the drop center rim flange, and force is applied to the center portion to force fit the flange portions of the wheel disc within the drop center flange. Since the wheel rim drop center flange and/or one or more of the wheel disc flange portions may be out of round, have galled areas, or have dirt or grit thereon, increased localized frictional resistance between the drop center flange and the annular flange portions can result during force fitting of the wheel disc within the wheel rim. This increased localized frictional resistance can cause the wheel disc center portion and flange portions to flex or twist relative to each other during force fitting so that the plane of the center portion is not parallel to the plane of a wheel rim terminal flange after assembly of the wheel disc within the wheel rim. This non-parallel relationship results in lateral runout which exceeds predetermined limits.
Murano et al U.S. Pat. No. 4,841,622, Apparatus For Interference-Fitting An Inner Member With An Annular Outer Member, discloses the force fitting of a wheel rim over a wheel disc while supporting the center portion of the wheel disc and the axially extending circular flange portions of the wheel disc. In Murano, the center portion of the wheel disc is fixedly supported on a press bed. The flange portions of the wheel disc are initially floatingly supported by air cylinders engaging the edges thereof. The air cylinders compensate for the varying axial extent of these flange portions. After the center portion is clamped against the fixed support, a valve in the air supply to the air cylinders is closed prior to force fitting the drop center flange of the wheel rim over the flange portions of the wheel disc. As previously mentioned, the flange portions of the wheel disc and/or the drop center flange of the wheel rim may be out of round or have galled areas or may have dirt or grit thereon so as to result in increased localized frictional resistance during force fitting of the wheel rim and wheel disc. Since air is compressible, the force resulting from this increased localized frictional resistance will axially compress one or more of the air cylinders and permit flexing or twisting of the center portion of the wheel disc relative to the flange portions during force fitting of the wheel rim over the flange portions of the wheel disc. This distortion of the center portion of the wheel disc would result in lateral runout problems. Additionally, while the Murano et al apparatus purports to be able to assemble the wheel disc within the wheel rim, this is impossible.
The wheel assembly apparatus of this invention force fits a wheel disc within a wheel rim to provide a vehicle wheel with minimum lateral runout. The apparatus provides minimum lateral runout vehicle wheels on a mass production basis while overcoming increased localized frictional resistance resulting from wheel discs and wheel rims which are out of round, have galled areas or have dirt or grit on their interfitted flange portions and drop center flange.
In the preferred embodiment of the invention, the terminal flange of the wheel rim is seated on a wheel rim support, such as a continuous or segmented ring, which is fixed to a main support, such as a press bed, and defines a fixed horizontal plane. A movable wheel disc support is mounted on the main support and extends axially through the wheel rim support and wheel rim. The wheel disc support defines a horizontal plane parallel to the plane of the wheel rim support and seats the axially outer face of the center portion of the wheel disc. The wheel disc support includes suitable guide pins to receive the bolt and/or axle openings of the wheel disc and orient the wheel disc relative to the rim, such as to the valve stem opening. Movement of the movable wheel disc support relative to the main support is resisted by springs or air cylinders. The axially extending flange portions of the wheel disc extend axially away from the center portion of the wheel disc.
A ram is movably mounted on the main support for vertical movement between a raised position, out of engagement with the axially inner face of the wheel disc center portion, and a lowered position in engagement with such axially inner face, generally opposite the wheel disc support to clamp the center portion therebetween. The ram defines a horizontal plane parallel to the plane of the wheel rim support and to the plane of the wheel disc support. A slide respective to each axially extending wheel disc flange portion is slidably mounted on the ram and connected to the piston of a hydraulic cylinder, also mounted to the ram. The hydraulic cylinders are connected to a source of hydraulic fluid and a valve controls the flow of fluid into and out of one side of each cylinder. When the valves are open, the slides and pistons are freely extendible and retractable relative to the ram. When the valves are closed, the slides and pistons are unitized with the ram despite compression forces thereon since hydraulic fluid is incompressible.
To assemble a wheel disc within a wheel rim, the wheel rim is seated on the wheel rim support and the center portion of the wheel disc is seated on the wheel disc support. The ram is in the raised position and the valves are open so that the pistons are freely movable relative to the cylinders and the slides are gravity extended relative to the ram. The ram is then initially lowered or moved toward the wheel disc. This will engage the gravity extended slides with the axial terminal edges of respective wheel disc flange portions. The pistons thereafter move within their respective cylinders and the slides retract relative to the ram as the ram continues to be lowered into engagement with the wheel disc center portion. All of the slides will not engage the axial terminal edges of their respective flange portions at the same time since such terminal edges do not all lie in the same radial plane due to manufacturing tolerances. When the ram engages the axially inner face of the wheel disc center portion, it clamps or holds the wheel disc center portion against the wheel disc support to locate such center portion in a plane parallel to the plane of the wheel rim support. Upon such engagement, the valves are closed to lock the slides and their pistons relative to the cylinders and ram so that the slides and ram are unitized and can thereafter apply a uniform pushing force on the center portion of the wheel disc and on the flange portions. This will prevent such portions of the wheel disc from flexing or distorting relative to each other, either during the force fitting operation or thereafter due to metal springback.
Thereafter, the ram, wheel disc, and wheel disc support are lowered or moved toward the wheel rim against the resistance of the springs or air cylinder of the wheel disc support. As this movement continues, the flange portions of the wheel disc will be force fitted within the drop center flange of the wheel rim. Since the slides are unitized with the ram and the center portion of the wheel disc cannot move relative to such flange portions, the wheel disc moves within the wheel rim drop center flange without twisting or flexing and with the center portion of the wheel disc being maintained in a plane parallel to the plane of the wheel rim support. Thus, the assembled wheel has the wheel rim thereof and wheel disc center portion thereof located in planes parallel to each other to reduce lateral runout to a minimum.
Should the wheel rim not lie flush against the wheel rim support so as not to be coplanar with the plane of such support, the initial frictional engagement of the flange portions of the wheel disc with the drop center flange will force the wheel rim into coplanar relationship with the plane of the wheel rim support.
Since it is impossible for the wheel disc center portion and flange portions to move relative to each other, the interference tolerance between the flange portions and the drop center flange of the wheel rim can be increased to increase the strength of the wheel. This also allows the wheel rim to be made of reduced thickness metal. Additionally, out of round or galled areas of the wheel disc flange portions or drop center flange or dirt or grit therebetween cannot affect the assembly of the wheel disc within the wheel rim or the maintenance of a parallel planar relationship therebetween.
Therefore, the primary feature of this invention is that it provides a wheel assembly apparatus which force fits a wheel disc within a wheel rim to provide a vehicle wheel with minimum lateral runout. Another feature is that a parallel planar relationship of the center portion of the wheel disc to the terminal flange of the wheel rim is established and maintained as the wheel disc is force fitted within the wheel rim. A further feature is that the relationship of the center portion of the wheel disc to the flange portions thereof is fixed and maintained despite high localized frictional resistance forces attempting to flex or distort these parts of the wheel disc relative to each other during force fitting of the wheel disc within the wheel rim. Yet another feature is that high localized frictional resistance forces resulting from galling or out of round areas of the wheel disc flange portions and/or wheel rim drop center flange or dirt or grit thereon are accommodated without sacrificing maintenance of the parallel planar relationship between the center portion of the wheel disc and the terminal flange of the wheel rim during assembly of the wheel disc within the wheel rim.
These and other features of the invention will be readily apparent from the following specification and drawings wherein: